1. Technical Field
This invention relates generally to internal combustion engines, and more particularly to pistons and to their method of construction.
2. Related Art
Engine manufacturers are encountering increasing demands to improve engine efficiencies and performance, including, but not limited to, improving fuel economy, improving fuel combustion, reducing oil consumption, increasing the exhaust temperature for subsequent use of the heat within the vehicle, increasing compression loads within the cylinder bores, decreasing weight and making engines more compact. Accordingly, it is desirable to increase the temperature and compression loads within the combustion chamber of the engine. However, by increasing the temperature and compression loads within the combustion chamber, the wear and physical demands on the piston are increased, particularly when the operating temperature of the piston exceeds 240-270 degrees Celsius, thereby reducing its potential useful life. A particular area for concern of elevated temperatures is along an upper combustion surface of the piston and within the internal region of the piston, such as an undercrown region of the piston.
Accordingly, it is known to promote cooling of the undercrown region via electrically powered oil pump systems that forcefully direct oil under pressure from an oil sump region upwardly into the undercrown region of the piston. Although known mechanical or electrically powered pumps can be effective at reducing the operating temperature of the piston, they come at a cost. Typically, the electrically powered pumps require about 2 to 3, kW of energy in a typical 6 cylinder heavy duty engine, and even more in larger engines. As such, the electrically powered pumps result in parasitic losses to the engine, which in turn results in reduced engine performance, reduced engine efficiency and reduced fuel economy.
A piston constructed in accordance with this invention overcomes at least the aforementioned disadvantages of known piston cooling systems, as will become apparent to those skilled in the art upon reading the disclosure and viewing the drawings herein.